Removing snapped drill bit ?
 

If anyone has a solution to removing a snapped drill bit from a cylinder head ( done while trying to tap out an already snapped bolt ) = I'm all ears.

Happened on a 4hp outboard - an OLDIE but a goodie..

Is there a drill bit that will drill through the snapped drill bit so I can then re-tap the hole ??

you might have to go at it with a dremel. then get a timesert kit and your good to go.

Depends on hardness and size of the bit that broke. I've used a smaller cobalt bit to start hole on the broken bit or bolt, and then used a screw remover bit and wrench to remove bolts and bits alike - but its a pain. imagine a cylinder head hole is probably 3/8" or so, so that's an advantage over something smaller. dremel with a diamond tip would probably start the extraction hole better than a even a cobalt drill bit. Good luck, sounds like a PITA..oops 4hp bolt might be a bit smaller...

Thanks guys - I like the dremel / diamond bit. I'll try it ! Totally PITA. 1972 !!!! 4hp evinrude - runs like a top for the 1 hour used seasonally when the wind totally dies on my day sailor.

It was running HOT when I went to winterize it - I had just replaced the impeller last year so I figured I'd check the cylinder / exhaust plate for blockage and gasket issues. Snapped bolt on inspection. All was OK in there anyway !

Dropped the lower unit. Turned out that the copper tube feeding the powerhead and fed by the impeller housing was clogged ! Straightened a hanger, unclogged it - but now this snapped bolt is allowing exhaust plate to leak !

Aaah tinkering. But, I figure even a pro would have had that same thing happen too. Wife thinks I'm insane. I try to explain, some guys watch sports or do crossword puzzles - I fix things ! You should see my fully restored 8 hp 26" snowblower ! I'm sick - I know !

I've be told an important reason for changing your impeller every year or so is to keep the lower unit bolts from corroding and snapping. Go figure.:( good luck tinkering

Used the diamond dremel - it did not cut but a benefit is that it loosened the bit and I was able to fish it out while twisting with two straightened dental picks.

Then I cleaned the hole with a tungsten bit. All tapped and done...

Thanks guys !

Glad to hear you got it taken care of without too much trouble.

You know those breaks can be hell. Lucky it was a bolt that snapped in a spot that the powerhead didn't have to come off to access it ( like 3 of the 8 are ) and that it was loose enough to get out that bit out. Otherwise I would have been in trouble.

Thx again.

When I break bits, I use a punch and hammer it into pieces to remove it. Less risk of damage to threads.

I spent about 35 years developing new jet engines that run so hot that conventional anti seize products don't work; in fact they would oxidize and actually make the problem worse! Other than heat and/or liquid nitrogen, and Zyglo fluid (used for florescent penetrant inspection), this is some of the best stuff we found: http://www.kanolabs.com/google/ Good hardware stores sometimes carry it but you can also order it from Eastwood http://www.eastwood.com/kroil-penetrating-oil.html